As Microsoft struggles to fight off several high-visibility patent lawsuits, an ophthalmologist in Wisconsin has filed another patent infringement suit that potentially could cost the software giant an eye-popping amount.

The suit, filed in U.S. District for the Western District of Wisconsin earlier this week, alleges that Microsoft's (NASDAQ: MSFT) Zune music player's "Buy from FM" feature infringes a pair of patents that were granted in 2002.

Further, the doctor -- Edward Yavitz of Rockford, Ill. -- claims he contacted Microsoft in 2006, pointing out that he owned the two patents. He said he suggested Microsoft make an inexpensive upgrade to the Zune player and negotiate deals with large radio broadcasters that would enable users to buy music they heard on the Zune's FM receiver, whether they knew the performer or not.

Once implemented, his letter to Microsoft said, a user could simply press the device's Zune button when that person heard a piece of music that he or she wanted. That would cause the Zune to either automatically purchase and download the music if the user was within range of a Wi-Fi hotspot, or would do it later when a connection with the music seller was available.

"THIS IS ALL POSSIBLE AND PATENTED ... SO IPOD and Google CAN'T DO IT, but Microsoft can, if you take the time to talk to me," Yavitz's letter said, according to the filing.

Yavitz said he never received any response from Microsoft, even after multiple attempts.

"I got no reply whatsoever," Yavitz told InternetNews.com.

However, two years later in September 2008, Microsoft announced the "Buy from FM" service.

"Starting next week, every Zune portable media player will let consumers wirelessly download or stream millions of songs on the go from thousands of wireless hot spots around the country. Free, powerful software and firmware updates will give Zune owners the ability to discover, tag and purchase songs directly from the built-in FM radio," said Microsoft's press release at the time.

Yavitz's suit also alleges that the feature is implemented in Zune HD devices, which shipped last September, replacing earlier versions of the player.

Broad enough to cover other technologies

In his suit, Yavitz asks for a permanent injunction against Microsoft selling the Zune with the allegedly infringing technology, along with treble damages, and court costs. He also said that his patents are broad enough that other broadcast technologies such as HD radio do not undercut the validity of his patents.

"I came up with the [patents] before there was even an iPod," Yavitz said, adding that his patents have another ten years to run. Yavitz also said he has gained a total of 36 patents over the years.

The suit appears to have gotten Microsoft's attention.

"They are definitely taking notice of it," Yavitz said, although he declined to characterize what kind of response the suit has elicited.

Yavitz said it's possible that Microsoft's change in attitude has to do with looking towards the future and the newly-announced Windows Phone 7 Series devices, which will include Zune-like features, including an FM radio.

"Windows Phone 7 has the potential of turning every phone into a Zune," Yavitz added. If the new phones take off, they could bring in a lot of income, which would make the two patents that much more valuable.

Microsoft officials declined to comment on the suit or its merits.

Stuart J. Johnston is a contributing writer at InternetNews.com, the news service of Internet.com, the network for technology professionals.